1. Field of the Invention
The present invention is based on a device and a method for cylinder-torque equalization of an internal combustion engine.
2. Description of Related Art
A method for cylinder-torque equalization of an internal combustion engine is already known from published German patent application document DE 198 28 279 A1. In order to make possible an operation low in exhaust gas using three-way catalytic converters, the internal combustion engine is operated at an average lambda value of 1. The average lambda value 1 is set by a lambda regulation. In this context, the distinction is made between the operating modes homogeneous operation and stratified operation. In stratified operation, the lambda value and the torque contribution of a single cylinder are essentially a function of the fuel quantity supplied. In homogeneous operation, the fuel quantity required to achieve the average lambda value 1 is first introduced by the lambda regulation into each cylinder of the internal combustion engine, as a function of the air quantity supplied to the cylinder. At the same time, in stratified operation, the torque contribution of a single cylinder is monitored by a cylinder-torque equalization function, using the irregular running signal. If the torque contribution of the individual cylinders deviate too greatly from one another, the torque contributions of the individual cylinders are set to be equal by regulating the fuel quantity. As a result of the cylinder-torque equalization function in stratified operation, adjustment values are available for the fuel quantity to be injected and the control signals of the fuel injectors, which may also be used in homogeneous operation or homogeneous lean operation of the internal combustion engine for cylinder-torque equalization.
At small differences between the individual cylinder torque contributions, exhaust gas created by the homogeneous combustion is not impaired or only little impaired, since a three-way catalytic converter, situated in the exhaust branch is still able to convert the exhaust gas. If the difference between cylinder-individual torque contributions becomes too great, not only is the fuel usage increased, but in addition, the exhaust gas emissions of the internal combustion engine may lie outside the legally specified limits.